I am finding new uses for Bit.ly all the time. The fact that you can track how many times a link has been clicked has a number of not-immediately-obvious uses. One example is a solution to a problem we all have at one time or another: wondering whether someone has read an email we sent.
Say you have emailed a business plan to an investor or sent an email to a girl you just met and are asking out for the first time. Chances are you will soon be in some degree of agony while you wait with baited breath for that reply…
Hack: Offer up a link(s) in the email shortened using Bit.ly. For example, rather than attaching your business plan, you could send someone to an FTP site, or let them access it via Google Documents. In either case, include the a Bit.ly URL and then check to see if anyone other than you has accessed that link.
Simple, stealth, effective.